Generally, the guide sleeve for guiding the spindle of the length-adjustable column for chairs has been widely used in manufacturing chairs or tables.
The guide sleeve used in the column is provided with a slide sleeve comprising 6 or more vertical guide webs on its internal surface, projected toward the central longitudinal axis, and the vertical grooves having a larger width than that of the guide webs, both of which, alternate in its order and the multiple ribs(rib web) are formed on the outer surface to receive and support the guide tube.
The guide sleeves having multiple ribs on the outer surface of the guide sleeve were disclosed in U.S. Pat. Nos. 3,923,280, 4,756,496, and 5,413,414. Among them, U.S. Pat. No. 5,413,414, as seen in the FIG. 1, which may be considered to be similar to this invention includes a guide sleeve(10) having a slide sleeve structure for guiding and supporting the spindle(20) in touch with the spindle, an outer tube(15) for receiving the slide sleeve, and the ribs(20) radially formed in the center of the spindle between the slide sleeve structure and the cover surface of the guide sleeve(10).
Further, the above slide sleeve structure, as seen in FIG. 2, has vertically formed guide webs(14) touching the spindle(20), the ribs(13) formed radially toward to the outer surface, and the vertical guide webs(13) formed radially on the internal surface projected toward the spindle(20) in the portion in line with the ribs(13).
In the above slide sleeve structure, the vertical guide webs(14) have smaller width than that of the vertical grooves (12) formed between the vertical guide webs(14). This guide sleeve(10) for length-adjustable chairs forms a conventional slide sleeve structure where the vertical guide webs(14) are projected toward the axis and radially in line with the ribs(13) and in touch the spindle(20).
Furthermore, since the respective components such as vertical guide webs(14) made of resin and ribs(13), and the spindle(20) made of metal are susceptible to temperature change, and cause the slide gap between the vertical guide webs and the spindle to increase and decrease with such temperature change, the conventional guide sleeve cannot maintain an optimal mobility.
With extremely hot temperature, the slide gap between the vertical guide web(14) and the spindle(20) decreases and tightens, and it becomes difficult to control and operate the up and down function of the spindle. The conventional guide sleeve does not consider the susceptibility of the material to the temperature change and thus, unreliable.
Moreover, the conventional device has a small area for the vertical guide webs(14) to touch the spindle(20) and this can cause the webs to easily chip during its up and down operation. Therefore, it is not durable.
Furthermore, the vertical grooves(20) between the vertical guide webs(14) have larger width than that of the vertical guide webs (14) and this makes it difficult to retain oil and therefore, it is difficult to prevent it from breaking and from the noise.
Accordingly, it is an object of this invention to provide a slide sleeve of the guide sleeve for a length-adjustable column for chairs designed in such a way that the slide sleeve of the spindle is not affected by the temperature change so as to guarantee the structural reliability and durability, and to overcome the problems of the conventional sleeve.
In order to achieve the above object, the guide sleeve for the length-adjustable chair of this invention constructed the vertical guide webs, which form radially and project toward the axis between the radial line of the ribs, so as to allow the ribs and the webs of the slide sleeve structure to respond to the change of temperature and thus, minimize the expanding and shrinking of material in the slide gap.